Contour copying lathe

ABSTRACT

A contour copying lathe has headstocks and tailstocks for rotating a model and at least one workpiece about parallel horizontal axes. A pair of angularly interconnected parallel arms are pivotal about a horizontal axis orthogonal to and spaced from the workpiece and model axes and are arranged vertically spaced from the tool and workpiece, respectively. The arm above the workpiece is provided at its free end with a tool rotated about an axis parallel to the pivot axis and orthogonal to the workpiece axis. The tool arm is provided with a feeler roller rotatable about the same axis as the tool. The arms are angularly interconnected so that the tool cuts into the workpiece the same contours as those felt by the tool arm. The tool is rotated at high speed so that its peripheral speed is many times the peripheral speed of the workpiece or the feed speed between it and the workpiece. It is possible to provide two such sets of arms, one for roughing in a workpiece and the other for finishing it, the latter following the former along the workpiece.

United States Patent [191 Schmidt Feb.4, 1975 1 4] CONTOUR COPYING LATHE [75] Inventor: Erich Schmidt, Wien, Austria [73] Assignee: Maschinenfabrik Zuchermann Komm-Ges. Wien, Wien, Austria 22 Filed: Mar.7,1973

21 Appl. No.: 338,814

[30] Foreign Application Priority Data Primary Examiner-Leonidas Vlachos Attorney, Agent, or Firm-Karl F. Ross; Herbert Dubno [57] ABSTRACT A contour copying lathe has headstocks and tailstocks for rotating a model and at least one workpiece about parallel horizontal axes. A pair of angularly interconnected parallel arms are pivotal about a horizontal axis orthogonal to and spaced from the workpiece and model axes and are arranged vertically spaced from the tool and workpiece, respectively. The arm above the workpiece is provided at its free end with a tool rotated about an axis parallel to the pivot axis and or thogonal to the workpiece axis. The tool arm is provided with a feeler roller rotatable about the same axis as the tool. The arms are angularly interconnected so that the tool cuts into the workpiece the same contours as those felt by the tool arm. The tool is rotated at high speed so that its peripheral speed is many times the peripheral speed of the workpiece or the feed speed between it and the workpiece. Itis possible to provide two such sets of arms, one for roughing in a workpiece and the other for finishing it, the latter following the former along the workpiece.

6 Claims, 7 Drawing Figures fall 777011;?

PATENTEUFEB 191s SHEET 10F 4 I (an M02152 PATENTEU 4|975 SHEET '2 OF 4 SHEET MP 4 R MUM V Q mm a 1 y &

PATENTEDFEB' 1 CONTOUR COPYING LATHE FIELD OF THE INVENTION The present invention relates to a contour-copying lathe. More specifically this invention concerns such a lathe used for producing finely finished duplicates in wood or the like of a model.

BACKGROUND OF THE INVENTION In the production of furniture parts and the like a model is generally made by hand, and a contourcopying lathe is used to reproduce this model. Such a lathe generally has a bed in which a plurality of workpieces can be rotated about coplanar parallel axis. The model is spanned in the device and is rotatable about an axis parallel to and coplanar with the workpiece axes. Several arms all pivotal about a common axis transverse to and usually above the rotation axes are all linked together and all have ends engageable with a respective workpiece or the model. These arms are carriedon a carriage which can be displaced along the bed. The arm engaging the model has at its end a feeler which is usually formed as a roller that rides on the surface of the model. The other arms are provided at their ends with tools rotatable about respective axes lying above the respective workpiece rotation axes in a vertical plane passing through the respective workpiece axis. The tool can be a milling head, sanding drum, or the like.

In use the model and workpieces are all rotated at the same peripheral speed or angular velocity, and the carriage is displaced slowly from one end to the other of the lathe. The end of the model arm is urged, usually simply by the weight of this arm, against the model so that the ends of the other arms are similarly urged against the workpieces. Since these other arms are provided at their ends with cutting tools, the workpieces are cut to a shape corresponding to that of the model. The model is usually made of wood, and the workpieces are similarly wooden, but it is not unknown to use such devices for machining synthetic resins or metals.

In another such copying arrangement the workpieces are displaced past fixed tools, these tools again being rotated about axes either parallel to the direction of workpiece advance, or at least coplanar therewith. Another arrangement used for producing turbine impellers has a tool disk which is rotated about an axis parallel to the rotation axis of the workpiece, but in the opposite direction. In this manner the scratches produced by the tool are circumferential on the finished product. Such a device has a tool counterbalanced by a weight so that it cannot be employed on irregularly shaped jobs, but only on regularly shaped articles like turbine impellers.

All of these prior-art devices rough-cut the workpieces very well, but none of them can be used to produce a fine finish on a wooden workpiece. Even when the finest abrasive is used the workpieces must be subsequently worked on, usually by hand, so as to have a good finish.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide an improved copying apparatus.

Another object is the provision of a system for producing a fine finish on a wooden workpiece with a contour-copying lathe.

SUMMARY OF THE INVENTION These objects are attained according to the present invention is an apparatus of the above-described general type wherein the tools are rotated about axes trans-v verse to the workpiece rotation axes at a peripheral speed many times greater than the peripheral speed of the workpieces and the speed of relative displacement between the tools and the workpieces, the workpieces and models being moved past the tools or vice versa. The rotation axis of each tool is substantially transverse to the rotation axis of its workpiece.

With such an arrangement the periphery of the tool will run virtually parallel to the grain of the workpiece, which is always arranged parallel to the rotation axis, so that a very fine finish can be produced.

The tools can be milling heads of steel, or sanding drums. It is also possible to use as a tool a contact drum over which is spanned an endless sanding belt so as to produce a very fine finish. The feeler on the end of the model arm is advantageously a roller.

According to another feature of this invention the arrangement described above can be employed on the same apparatus with a rough-cutting device either made according to the present invention, or, as is known in the prior art, that is rotatable about an axis transverse to the workpiece rotation axis. In either case the fine-finishing device according to the present invention will operate on the rough-cut workpiece either by following behind it a short distance or by finishing it on a separate cut in the same or the opposite direction.

DESCRIPTION OF THE DRAWING The above and other objects, features, and advantages will become more readily apparent from the following description reference being made to the accompanying drawing in which:

FIGS. 1 and 2 are side-elevational and top views, respectfully, of an embodiment of the present invention;

FIG. 3 is a diagram illustrating the operation of the device of FIGS. 1 and 2;

FIG. 4 is a side-elevational view of another embodiment of the present invention; and

FIGS. 5, 6, and 7 are side, top and cross-sectional views, respectively, of yet another embodiment of the present invention.

SPECIFIC DESCRIPTION As shown in FIGS. 1 and 2 the apparatus according to the present invention has a frame 1 on which two parallel cross members 2 and 3 are slidable and lockable on tie-rod guides 4. The cross member 2 is provided with three headstocks 5 and the member 3 with three tailstocks 6 in line with these headstocks. Spannedv between the central headstock and tailstock is a model 7, the adjacent headstocks and tailstacks receiving wooden workpiece blanks 8 and 9 which are rough cut to a slightly greater size than desired in the end product. All of these elements are rotatable about respective parallel, coplanar and horizontal axes A. A hydraulic piston 10 at each tailstock 6 serves to clamp the elements 7-9 tightly in place, and sprocket wheels 11 connected to the headstocks 5 are connected by a chain 12 to a motor 13 to rotate them all at the same peripheral speed and all in the same direction.

A second pair of guides 14 lying outside the guides 4 each support a respective carriage half 15 and 15 which form a carriage 15 and are connected together under the lathe bed by a crosspiece through which a feed screw 16 passes. A gear 17 on the end of the feedscrew 16 meshes with reduction gears 18 connected to a motor 19 so that this motor can move the carriage 15 back and forth parallel to the axes A. A process controller 21 switches the motor 19 on and off.

Extending between the carriages 15 is a rod 22 having an axis A which is parallel to the common plane of the axis A and orthogonal to these axes A. A heavy steel sleeve 23 pivotal on this rod 22 is formed with three parallel arms 24, 25, and 26 each formed at its free end with a respective fork 27, 28, and 29 defining an axis A" parallel to the axis A. The central fork 28 receives a hard rubber roller 30 which is freely rotatable about the axis A" and normally rides on the model 7.

The fork 27 receives a roller 32 which is driven to rotate about the axis A" by a motor 45. The roller 32 is operated by a drive pulley 39 connected via a V-belt 40 to another pulley 42 journaled on the rod.22. A pulley 42 also journaled on the rod 22 is rotationally fixed to the pulley 41 and is connected through another V-belt 43 to a pulley 44 carried on the motor 45 which is fixed on the respective carriage half 15', 15". Spanned over the roller 32 is an endless sanding belt 33 which also runs over a roller 34 rotatable about an axle 38 on one end of a two-arm lever 35 itself pivoted on an upright 36 from arm 24. A spring 35 or pneumatic device serves to bias the axle 38 upwardly so as to keep the sandingbelt 33 tight.

The other fork 29 carries a steel milling head 31 which is driven by a drive arrangement 39-45 identical to that described above, and also controlled by the programmer 21.

In operation the carriage 15 is backed up to the extreme right hand end of feed screw 16, and the motors 45 and 19 are started, after the free ends of the arms 24-26 are dropped down so that at least the tools 33 and 31 come into contact with the workpieces 8 and 9. The carriage 15 is moved in direction D at a speed V of 4.54 meters/minute, and the tools 32 and 31 at a peripheral speed V of 1,353 meters/minute. The elements 7-9 are rotated to have a peripheral speed V, at the location indicated of 27.9 meters/minute. With these speeds the minute scratches produced by the abrasive on the belt 33 or by the surface of the milling head 31 will extend at an angle a of 112 to a plane through the axis A. Thus the workpieces will have an extremely smooth finish with the minor marks from the abrasive completely hidden in the grain.

In the embodiment described above the peripheral speed V of the tool is some 300 times greater than the advance speed V of the carriage, and some 48 times greater thzn the peripheral speed V of the element 8. It has been found necessary to maintain a multiple of at least 20:] for v.=v., and at least 100:1 for V :V Obviously the first-mentioned ratio is the most critical since it is what largely determines the angle a which in turn determines the quality of the finish.

In FIG. 4 structure identical to that of FIGS. l-3 is given the same reference numerals. This arrangement rough cuts and fine finishes workpieces in-one pass. In

this setup the workpieces and model are spanned in a frame 46 which is displaceable parallel to the axes A by a pinion 47 engaging in a rack 48. The pivot axle 22 of the arm 24 is rotatable in a fixed support 49 so that the motor 45 is also stationary. The belt 33 is in this arrangement a very coarse grit so that it serves for roughing-in the workpiece, the drum 32 is also slightly smaller in diameter than the corresponding feeler roller.

Underneath the model 7 is provided an arrangement for fine-finishing the roughly cut workpieces. Three arms 51, only one of which is shown, are provided in much the same array as in FIG. 1. These arms are vertically pivotal about a horizontal axis 53 passing through a horizontal sleeve 52 from which the arms 51 extend. The axle 53 is rotatable in fixed end members 54 and functions also as a shaft for the pulleys of the V-belt drive 55 and 56 which connects the abrasive tool 50 with the motor 57. The tool 32 is urged by its own weight against the workpiece 8, but the tool 50 is urged upwardly by a hydraulic cylinder 58, although a spring would be equally employable. It is also possible to form the arm 51 as a two-arm lever, as shown in dot-dash lines, and mount the motor on its end so that this motor acts as a weight or counterbalance urging the tool 50 upwardly. During the return motion of the carriage 46 the tools 32 and 50 are moved away from the workpieces. This is effected by a return guide shown in dotdash lines at 59 and 60 which engages with pawls behind slide pins 61 and 62 in the end portions of the travel of the carriage 46.

In order that the two tools 32 and 50 do not interfere with each other they are spaced axially in the direction of travel by a distance a, with the rough-cutting tool 32 ahead the finish cutting tool 50 behind, relative to the direction of travel D. In addition the model 7 is formed as shown in dot-dash lines with flared ends 63 and 64. The flared end 64 prevents the tool 50 from riding in on the headstock at the start of a pass, and the end 63 prevents the tool 32 from riding in on the tailstock at the end of the pass.

FIGS. 5-7 show another embodiment of the invention wherein workpieces are rough cut and finished in one pass. Reference numerals identical to those of FIG. 1 indicate functionally identical structure. In this arrangement the upper carriage 15 is provided with three arms 65-67 roughly equivalent to the arms 24-26. These arms are connected together at flanges 68, 69, and and have end pins 71 journaled in the carriage halves 15, 15". Each such arm is provided with a respective spindle 72-74. The spindle 73 of the central arm 66 is freely rotatable and carries a copying roll 75. The other two spindles 72 and 74 each carry on one end a heavy-duty milling disk 76 and on the other end a V-belt pulley 77. A motor having a drive pulley 79 is connected by a V-belt 78 to each such pulley 77, with the pivot axis A passing roughly through the belt 78 where it engages the pulley 77 so as to permit widest possible pivoting of the arms 64-66. In the illustrated embodiment the tools 76 can rise some mm so as to accommodate very large workpieces. Since the length of the arms is many times the radial spacing between the periphery of the wheel 77 and its rotation axis, the belt 78 is not unduly strained when the tool head is lifted. These milling heads 76 cut away the workpieces 8 and 9 in a manner known per se, i.e., by rotation of the'tool about in an axis lying in a vertical plane passing through the rotation axis of the workpiece.

Underneath the device there is provided a carriage 83 which rides on guides 82 and is displaced back and forth by a feed screw 16 as shown in FIG. 1. This arrangement serves to fine-finish the workpieces 8 and 9. it has three parallel arms 86 extending from a sleeve 85 pivotal about a horizontal axle 84. The central arm carries a copying roller 81 and the two outer arms are provided with rolls 87 over which are spanned sandpaper belts 88. The roller 87 is itself driven by a belt 89 in turn driven by a belt 90 driven by a motor 91 carried on the slide 83. A combination spring-loaded and pneumatic cylinder 92 is provided on each arm 86 to urge the rolls 87 against the undersides of the workpieces 8 and 9.

Once again the upper and lower carriages are driven so that the roughing tools 76 precede the fine-finishing belts 88 by a distance a. This can be effected by simply driving them one behind the other, or only one need be driven and the two carriages and 83 can be connected together by a bar as shown in dot-dash lines at 93.

In this arrangement the two operations can take place simultaneously, or the fine-finishing can be made on a second return pass over the workpieces to prevent any chips from the milling heads from getting into the fine-finishing tools.

1 claim:

1. A contour-copying machine comprising:

' means for supporting a model and a workpiece rotatably about parallel respective model and workpiece axes;

means for rotating said model and said workpiece about their respective axes at a first peripheral speed;

means defining a pivot axis substantially orthogonal to said model and workpiece axes;

means for relatively displacing said pivot axis and said model and workpiece axes at a feed speed parallel to said modeland workpiece axes;

a model arm swingable about said pivot axis and having a feeler and engageable with said model;

a workpiece arm pivotal about said pivot axis and angularly fixed to said model arm, said workpiece arm having a tool and engageable with said workpiece;

means for urging said feeler end and said tool end against said model and said workpiece, respectively;

a tool at said tool end of said workpiece arm rotatable about a tool axis transverse to said workpiece axis and parallel substantially to said pivot axis and comprising a' rotatable drum, an endless sanding belt spanned over said drum, and means on said I workpiece arm for maintaining said belt tight about said drum;

means for rotating said tool drum about said tool axis at a second peripheral speed many times greater than said first peripheral speed and said feed speed for machining said workpiece and reproducing therein the contours of said model;

means defining a second pivot axis transverse to said model and workpiece axes;

means for relatively displacing said second pivot axis and said model and workpiece axes at said feed speed parallel to said model and workpiece axes;

a second model arm pivotal about said second pivot axis and having a feeler end engageable with said model;

a second workpiece arm pivotal about said second pivot axis and angularly fixed to said second model arm, said second workpiece arm having a tool end engageable with said workpiece;

means for urging said feeler end and said tool end of said second arms against said model and said workpiece, respectively;

a second tool at said tool end of said second workpiece arm and rotatable about a second tool axis; and

means for rotating said second tool about said second tool axis, said second tool being disposed ahead of the first-mentioned tool with reference to the direction of relative displacement of said second pivot axis, said second tool having a coarser material-removal characteristic than said first tool.

2. The machine defined in claim 1 wherein said second tool axis is coplanar with said workpiece axis.

3. The machine defined in claim 1 wherein said second tool axis is transverse to said workpiece axis.

4. The machine defined in claim 2 wherein said second tool is a milling head.

5. The lathe defined in claim 3 wherein both of said tools are provided with such sanding belts, the belt of said second tool having a coarser grit than the belt of said first too].

6. The machine defined in claim 1, further comprising contour extensions on opposite ends of said model and projecting axially therebeyond by a distance at least equal to the axial spacing of the first mentioned tool from the second tool for supporting the former during continued operation of the latter and vice versa. 

1. A contour-copying machine comprising: means for supporting a model and a workpiece rotatably about parallel respective model and workpiece axes; means for rotating said model and said workpiece about their respective axes at a first peripheral speed; means defining a pivot axis substantially orthogonal to said model and workpiece axes; means for relatively displacing said pivot axis and said model and workpiece axes at a feed speed parallel to said model and workpiece axes; a model arm swingable about said pivot axis and having a feeler and engageable with said model; a workpiece arm pivotal about said pivot axis and angularly fixed to said model arm, said workpiece arm having a tool and engageable with said workpiece; means for urging said feeler end and said tool end against said model and said workpiece, respectively; a tool at said tool end of said workpiece arm rotatable about a tool axis transverse to said workpiece axis and parallel substantially to said pivot axis and comprising a rotatable drum, an endless sanding belt spanned over said drum, and means on said workpiece arm for maintaining said belt tight about said drum; means for rotating said tool drum about said tool axis at a second peripheral speed many times greater than said first peripheral speed and said feed speed for machining said workpiece and reproducing therein the contours of said model; means defining a second pivot axis transverse to said model and workpiece axes; means for relatively displacing said second pivot axis and said model and workpiece axes at said feed speed parallel to said model and workpiece axes; a second model arm pivotal about said second pivot axis and having a feeler end engageable with said model; a second workpiece arm pivotal about said second pivot axis and angularly fixed to said second model arm, said second workpiece arm having a tool end engageable with said workpiece; means for urging said feeler end and said tool end of said second arms against said model and said workpiece, respectively; a second tool at said tool end of said second workpiece arm and rotatable about a second tool axis; and means for rotating said second tool about said second tool axis, said second tool being disposed ahead of the first-mentioned tool with reference to the direction of relative displacement of said second pivot axis, said second tool having a coarser material-removal characteristic than said first tool.
 2. The machine defined in claim 1 wherein said second tool axis is coplanar with said workpiece axis.
 3. The machine defined in claim 1 wherein said second tool axis is transverse to said workpiece axis.
 4. The machine defined in claim 2 wherein said second tool is a milling head.
 5. The lathe defined in claim 3 wherein both of said tools are provided with such sanding belts, the belt of said second tool having a coarser grit than the belt of said first tool.
 6. The machine defined in claim 1, further comprising contour extensions on opposite ends of said model and projecting axially therebeyond by a distance at least equal to the axial spacing of the first mentioned tool from the second tool for supporting the former during continued operation of the latter and vice versa. 